Air regulator for furnaces



Feb. 5, 1935. G. A. KoHoUT AIR REGULATOR FOR FURNACE'S Filed Sept. l, 1932 2 Sheets-Sheet l fr b Feb. 5, 1935. G. A. KOHOUT AIR REGULATOR FOR FURNACES Filed Sept. l, 1952 2 Sheets-Sheet 2 o mm, o o o n uw jllllllllllllll/ll/ Patented Feb. 5, 1935 UNITED STATES PATENT OFFICE 2 Claims.

My invention relates to air regulating means for furnaces and has for its principal object the provision of a novel control system whereby the ingress of air to the furnace and the outlet of V5.A the gaseous products of combustion from the furnace may be regulated together to avoid excess losses owing to too much or too little air in the furnace.

A supply of excess air to a furnace above the 1ro requirements necessary for the proper combustion of the fuel involves a tremendous waste of heat. Also, the lack of air necessary for a proper combustion results in an imperfect or partial combustion only and also causes a. great waste of 145mY heat energy.

My invention contemplates as its principal purpose the provision of a novel means whereby the inlet or outlet or both of the furnace may be controlled and regulated in combination with 2.0V means `for indicating the pressure drop between different parts of the furnace so that the draft of the furnace may be properly set forthe most efrcient operation whether it be during the building up of the nre when new fuel is being fed into the furnace or during a more or less quiet period when no new fuel is being added.

Other and more specific objects and advantages of the invention will appear as the` description proceeds in connection with the accompanying 3.0:'. drawings. It is to be understood, however, that the drawings and description are illustrative only and are not to be taken as limiting the invention except in so far as it is limited by the claims.

In the drawingswith my control means, the back part of the furnace which does not enter into the combination in any way except in its usual function being broken away; i

Fig. 2 is an enlarged front view of aV portion of the control mechanism; and

Fig. 3 is aside View partly in section ofthe mechanism shown in Fig. 2.

Fig. 4 is an enlarged detail section along line 45" 4-4 of Fig. 3.

Referring now in detail tothe drawings, I show the invention as applied to a furnace 5 equipped with an underfeed stoker 6 of the screw type having a hopper at 7 for receiving coal. The fuel bed is shown dotted at 8. The air inlet duct is shown at 9 coming from a motor operated fan at 10, the motor receiving its power from a threephase line over the conductors 11, 12, and 13. The passage of the gas through the furnace as indicated by the arrows brings it finally to the stack Fig. 1 is an assembled View of a furnace equipped.

at 14 in which is located a' control. damper 15. The fan 10 forces air into the furnace while the damper I5 controls the outlet of the air and the other gases produced by combustion through the stack.

Mounted on a panel adjacent to or upon the furnace is a control mechanism by means of which the position of the damper l5 may be controlled in conjunction Withthe fan 1U which forces air into the furnace. The lines 11, 12, and 13 10 whichV feed current to the fan motor are connected through the relay switch 27 to the incoming power lines 28, 29, and 3U, and this switch 27` may be controlled by means of the relay coil 31 and another suitable switch 32 which is prefer- 15 ably controlled by the heat condition of the furnace as for example by boiler pressure or by furnace temperature. The switch 32, it will be noted, is connected across the two lines 29 and so as to energize coil 31 when it is closed. Coil 2g 33 is also energized by the closing of switch 32 to control switch 34 which is located in one of the' feed lines 35 of the lines 35 and 36 feeding current to the motor 37 which is mounted directly beneath the indicator 17`. Lines 36 and 35 may 254 be connected to any suitable source of potential such as the usual 110 volt supply line. I have shown the motor operated fan 1C as being operated from a three-phase source of current but it is obvious `that a single phase orv other sourcer 3o of current such as direct current might be used in the same fashion.4

The action is asfollows: When switch 32 isl closedr the contacts of switch 27 are closed' owing to the fact that coil 3l. is energized and the Ian' 35a 10 is operated. Also, when switch 32` is closed, coil 33 is energized and switch 34 is therefore closed to energize the motor 37 for a purpose which willpresently appear. In conjunction with the leads 35 and 36 to the motor, leads 38 and 40 39V are connected in parallel with the' motor leads and they in turn lead to a switch 40' which is con-- trolled by thev motor 37'.

The manner of control of switch 40 by motor 37' is best illustratedl in Fig. 3. The motor 37 drives a suitable reduction gear 4l which in turn drives al cam 42 in the direction of theY arrow as shown in Fig. 3'. This cam 4-2 is adapted' on each revolution to strike the lever arm 43 which is 50 connected to one contact 44 of switch 40 so as to rock this contact away from the other contact 45. The weight of arm 43 is sufficient to cause it to swing contact 44 back into engagement with contact 45 after the cam 42 moves out of the way. 55

In this way, the circuit through switch 40 is broken on each revolution of the cam 42.

The result is'that when switch 34 is opened, if this does not happen to occur when switch 40 is open that is when the cam is in engagement with arm 43, the motor will still receive current over a line extending from lead 35 around switch 34 over lead 39 to switch 40 and from switch 40 over leads 38 and 3 5' to themotor and then from the motor over the lead 3,6 to the other side of the source of current. Motor 37, therefore, remains energized any time switch 34 opens untilv thek cam 42 is in raised position, that is, in a position" oppositeto that shownin Fig. 3. 1 l

The purpose of this stopping the motor withthe cam raised is to permit the link 46 to rise. This link, it will be noted is slotted as shownatl47,

and the slot ts over a pin 48 on the cam 42 so that while the motor 37 is running `link k46 yisy pulled down to the position shown in Fig. 3 upon each 'revolution 'of' the fcam 42.

l 'As shown most clearly in'Fig's. f11 and 3, the pulling down of link 46 pulls arm, 49 down to its lowermost'po'sition' and, throughlthe means of theA connector link 50 and the exible leadl 5,1, holds 'the lever arm 52 onthe Vdamperfl` up in the po'sition'shovminliig. l so "'as t0, maintain the "damper in open position. `The weight 53 alsofconnected to armj52 .tends to move theyarmr 52 vdown and'close the damper at all times. 4 9, however,` is connected by means ofthe link 54 (see Fig.l y3) toI the piston 55 of` ay dash' pot structure 56 such as that shown for example in my' prior'copending application SerialNo. 589,078, 3'5V filed January 27, `1932', for Grate control.

yThe function of the dash pot 56 is to oppose rapid rise of arm 57. ,The Ylever arml 57 has a lip 53that rides on arm A49to`pull it down when the furnace starts. `Arm 49 is fixed on shaft 59,

but ami 571s not. shaft 59 also has nxdiner'erf Upon the initial 'rotationlof cam 42, the arm'49 ispulled down.,by 1link46,`farm 57, andlug 58"' thus opening .the'dampen The 4arm 49 is pre-U` 5.5,. switch closed,l the relay 31 is energized over a circuit extending. from line 29 `throughswitch 32, relay 31, toline 30. The contacts of switch 27 aretherefore closed t'osupply current/to the ian motor over lines 11, 12, and`13. Relay coil 33 I isalso energized when {switch 32 is closed and holds switch 34 closed to supplycurrent to motor 3 7 over lines 35, 35 and..36.

Now so long as switch 32 remains closed, the fan motor 10 andmotor371will be operated. Air will -be supplied to the furnace by the fan, and the damper will remain open. Motor 37 rotates cam 42, and pin 48 on the cam keeps pulling link 46 down, and link id througharmf 57 and legs 58 keep arm 49 from rising to close the damper.

When kthe pressure controlling switch 3.2 rises high enough to open this switch, the armatures of relay switch 27 drop back because relay 31 is de raises arm 43 to separate contacts 44 and 45 and raises pin 48 up so that link 46 may rise, the

motor 37 is stopped and the damper rcontrolling arm 49 can be moved'up by means of arm 60 and spring-61,- to allow the damper to move toward closed position.l

When the pressure againr drops and switch 32 y again closes, relays .3l and 33 again attract their armatures toenergize the fan motor and motor 37. Motor 37 then turns cam 42 to draw down.

link 46an'd open the damper. `VThe operation of the fan k10 continues untilthe `pressure switch 32 again' opens when the vcycle fof Aoperations `just describedis repeated;v ,',Motor 37 continues kto operate the [cam `42, which, upon the upward movement of pin 48, would permit upward movement of link 46, but extensive upward movementV of member 46 during the upper part of the cycle of pin 48 would be presented bythe dash pot 56. From the above description, it will be seen that the starting of the ysystem causes the immediate opening of *the damper rto, take care ofthe air driven into the furnace'by vthe fan. jThe connection of arm 4 9 with 50 permits proper adjustment of the damper position by shifting the pin on the arm 49 to diiierent holes 62 inthe link 5(7).H The draft of the furnace can thus be regulated to` the proper value. Then, whenrv the forced draft is stopped,the damper will remain openi'until vdamper is gradually closed'. "Having thus described one specic form of my invention, what Ijclaimas newy and desire `to secure kby Letters Patent is? l "motor 37 moves cam-42 toits upper position, and' v` then switch 40 opens the circuit o-f motor 37 andI stops it."'This-allows arm 49 to rise, and the,

l. An'air regulating system for furnacesA comprising a fanfor'forcing air into the furnace, a

power device driving said fan, a damperv con--4 trolling the outlet of gaseous products of combustion fromvthe furnace, and means for actuating said fan and damper comprising mechanism connected to said damper ynormally holding it open,`

and means 4releasing l'said mechanism f upon stopping of `said fan to causeclosing` movement of 'saidl damperfa predetermined time after 'the fan is shut off.

n 2. An air regulating system for furnaces having means for forcing air ninto the furnace, and a damper controlling the outlet of gaseous products of lcombustion from the'furnace, said system including-control mechanism interconnecting `thek air forcing means and the damper for moving `the damper toward closing position la predetermined time after cuttingy off the supply airf to the furnace.

GEORGE A. KOHOUT.- 

